Device for the Removal of Thrombi

ABSTRACT

The invention relates to a device provided with one or several distal elements ( 27 ), with the distal element ( 27 ) comprising at least two core wires ( 14 ) which are twisted around each other and between which fibers ( 6 ) are arranged transversely to the extension of the core wires ( 14 ), with said fibers ( 6 ) being twisted together with the core wires ( 14 ) so that the fibers ( 6 ) project radially outward from the distal element ( 27 ).

The invention relates to a device for the removal of foreign bodies andthrombi from body cavities and blood vessels using a guide wire providedwith one or several distal elements.

Thromboembolic diseases such as cardiac infarction, pulmonary embolism,peripheral thrombosis, organ embolisms etc. are typically caused by athromboembolism (hereinafter for short thromb or thrombus), i.e. avisco-elastic blood clot comprising platelets, fibrinogen, coagulationfactors etc. forming in a blood vessel which it obstructs either whollyor in part. The obstruction of organ arteries also leads to the supplyof oxygen and nutrients to the associated tissue being interrupted. Thedisorder of the functional metabolism linked with functional losses isclosely followed by a failure of the structural metabolism resulting inthe relevant tissue becoming destroyed (infarction). Organs mostfrequently affected in this way are the heart and the brain.Nevertheless, the arteries of the limbs as well as pulmonary arteriesare also impaired. Venous thromboses and thromboembolic occlusions arefrequently occurring in the leg and pelvic veins. The disease pattern ofthe thrombotic occlusion of an intracranial sinus may lead to severeintracerebral hemorrhage due to a failure of venous drainage of braintissue.

In view of the severity of the disease patterns associated withthromboembolism and the prevalence rate of such diseases varioustechniques have been developed aimed at dissolving or removing thrombi.

It is known in this context to treat such patients with thrombolyticagents such as streptokinase or urokinase or anticoagulants intended toachieve thrombolysis or limit the growth of thrombi. Since treatmentmethods of this kind are usually very time consuming they are frequentlycombined with invasions aimed at reducing the size of or removing thethrombus or embolus mechanically.

Aside from open surgical operations prior art techniques more and moreembrace the use of transluminal or endovascular, catheter-guidedinterventional therapy methods because these are of less invasivenature. It is thus known to remove the thrombus from the patient's bodyby means of vacuum producing suction catheters or mechanically usingcatheters provided with capturing cages, helixes, hooks or similarelements; refer to U.S. Pat. No. 6,245,089 B1, U.S. Pat. No. 5,171,233A1, Thomas E. Mayer et al., Stroke 2002 (9), 2232.

Disadvantages associated with the known transluminal devices are thatwith said devices it is often impossible to remove the thromb completelyand, moreover, there is a risk of the thromb or fragments of it beingreleased into the blood stream thus passing on to vessels of smallerlumen which are more difficult to be reached and treated. Furthermore,due to their size and/or low flexibility the devices known from priorart are only inadequately suited for the removal of thrombi from greatlyconvoluted vessels or those of particularly small lumen such as those inthe brain.

From US 2002/0049452 a device with a catheter is known for the removalof thrombi to which distal end capture arms made of shape-memorymaterial are attached which in their compressed state rest against thecatheter and when expanded extend radially from the catheter outwards.When in expanded position which is caused by the body temperature thecapture arms are intended to get caught in the thrombus and then retractit out of the blood vessel as the catheter is pulled back into anothercatheter. The drawback associated with this device is, however, that inorder to cool and thus keep the capture arms below trans-formationtemperature before they are released into the blood stream it musteither be moved past the thrombus in a secondary catheter which bringsabout the cooling effect, or a heating system has to be arranged insidethe catheter provided with the capture arms that enables thetransformation temperature to be attained when the thrombus has beenreached. Not only are the design requirements of this configuration veryhigh and thus prone to disturbances it is also the sheer physical sizeof this device that rules out a treatment of vessels having aparticularly small lumen.

In view of the disadvantages of these prior art devices it is thus theobject of the invention to provide a device for the removal of foreignbodies and thrombi from body cavities and blood vessels which alleviatesthe surgical risk existing when removing thrombi and allows thetreatment of vessels of especially small lumen.

According to the invention this objective is reached by providing adevice for the removal of foreign bodies and thrombi from body cavitiesand blood vessels using a guide wire and one or several distal elementsthat comprise at least two core wires which are twisted around eachother and between which fibers are arranged transversely to theextension of the core wires, with said fibers being twisted togetherwith the core wires, so that the fibers project radially outward fromthe distal element.

The distal element thus has the form of a brush provided withbristle-like outwardly projecting fibers. The fibers serve the purposeof capturing and stabilizing a thrombus in that they hook themselvesinto the thrombus and in this manner facilitate its retrieval. At thesame time the fibers/bristles are designed so as to be flexible so thatdue to the mechanical resistance in proximal direction they pressagainst the distal element when the device is moved forward. When theexternal strain caused by the micro-catheter is omitted the brushunfolds to assume its full brush structure. Accordingly, to fulfilltheir intended purpose of securing the thrombus the fibers must haveadequate stiffness but at the same time must be sufficiently flexibleand bendable so that they can be passed through a catheter and do notdamage the vessel walls.

The fibers or bristles are suited to capture and stabilize a thrombus,especially if they are made of or finished with thrombogeneousmaterials.

The fibers/bristles may also consist of a natural substance, polymermaterial, metal, ceramic material, glass or combinations thereof.Especially preferred are polymer materials.

Suitable materials in this respect are primarily polyurethane,polyacrylics, polyester, polytetrafluoroethylene, polyamide orpolyethylene and, due to its peptide-like bond structure, most notablypolyurethane and polyamide, e.g. nylon, which enable the thrombus toexcellently attach/adhere to the fibers.

Aside from polymer materials metals also well suited for the intendedpurpose. Suitable metallic materials for treatment purposes are allmetals that do not have detrimental effects on the patients. Especiallysuited for the described purpose are stainless steel fibers made ofmetal alloys having shape-memory properties such as for example nitinolfibers. Fibers made of shape-memory materials offer the advantage thatwhen under the external strain exerted by a micro-catheter they areinitially shaped to fit closely and after having been released from themicro-catheter assume a second orthogonal shape allowing them to stickout freely. Furthermore, gold and platinum are suitable materials aswell. Also suited are ceramic materials, fiber glass and carbon fibers.

Particularly suitable for the treatment of vessels of especially smalllumen are fibers having a length of 0.5 to 6 mm and preferably 0.5 to 3mm so that an outer diameter of 1 to maximum 12 mm of the fiber-carryingpart of the distal element is attained even when the fibers are arrangedradially. For a particularly atraumatic treatment such outer diametershould be sized slightly smaller than the inner diameter of the relevantblood vessel.

Expediently, the fibers extend over a length of the distal element whichranges between 0.5 and 5 cm. To make sure the thrombus is sufficientlyanchored it is expedient if the fibers are arranged on the distalelement of the guide wire with a density ranging between 20 and 100 percm.

The fibers or bristles to be used according to the invention preferablyproject at an angle ranging between 70° and 110°, preferably at an angleof between 80° and 90° from the longitudinal axis of the device. Theseangle indications are to be understood such that angles<90° characterizea proximal orientation of the fibers whereas angles>90° signify a distalorientation of the fibers. Embodiments providing for an angle which isslightly smaller than 90° are particularly atraumatic when being movedinto the vessel or through the thrombus and at the same time result inan especially effective anchoring within the thrombus when being pulledout of the blood vessel.

Expediently, the guide wire is made of a medical stainless steel orshape-memory material, preferably nitinol. It is expedient in this caseto provide a guide wire having an outer diameter ranging between 0.2 and0.4, preferably 0.22 and 0.27 mm. A typical guide wire length rangesbetween 50 and 180 cm, but may as well amount to several meters.

As per a particularly preferred embodiment of the device the fibers arecoated. For example, this coating may be a neutral one consisting ofParylene or polytetrafluoroethylene (Teflon), but may also be comprisedof collagen or may be a coating of a material conducive to bloodcoagulation, preferably having one or several coagulation factors. Thisembodiment serves to strengthen the anchorage of the fibers inside thethrombus and alleviates the risk of the thrombus disintegrating to suchan extent that fragments of it remain in the blood vessel or may beallowed to be released in the blood stream.

Surprisingly, it has been found that a thrombogeneous finishing of thefibers/bristles resulted in a significant stabilization of the thrombusat the device according to the invention. In this context it is left tothe surgeon to bring the inventive device into contact with the thrombusand maintain this contact for a certain period of time thus allowing thethrombogeneous elements to promote an “adherence” of the thrombus to thedevice. Such an adherence to thrombogeneous fibers/bristles is achievedafter a relatively short period, even within a few minutes at times. Notonly does this preclude the disintegration of the thrombus as it isencountered with many commercially available devices, also theretraction of the thrombus into the catheter and its extraction from thevascular system is facilitated in this manner. Especially suitedthrombogeneous materials and coatings for this purpose are known fromliterature to those skilled in the art. Especially suitable to this endare, for example, one or several of the factors fibrin, thrombin, factorXIII and/or factor VIII.

The following procedure is to be adopted when using the invention: Thedevice is transferred to the application site with the aid of asmall-lumen micro-catheter. The device situated inside themicro-catheter may either be 1) initially maneuvered to the distallocation of the thrombus and then retracted, 2) released from themicro-catheter in the area of the thrombus, or 3) pushed out of themicro-catheter at a point proximal to the thrombus and then penetratethe thrombus anterogradedly. When moving the device forward the flexiblefibers are pressed onto the distal element in proximal direction due tothe mechanical resistance encountered, and when the device is retractedthey assume an upright position, hook themselves into the thrombus andthus aid the retraction into a micro-catheter larger than the oneoriginally used. Said larger catheter is usually a guide catheter bymeans of which a micro-catheter can be introduced coaxially which inturn is used to bring the device to the target area. The thrombus thussecured via the device will then preferably be retracted into the guidecatheter and contained in this catheter eliminated from the body.

In the context of this invention the terms “distal” and “proximal” areto be understood as viewed from the direction of the attendingphysician. The distal end is thus the end situated away from theattending physician which relates to the components of the deviceadvanced farther into the blood vessel system whereas proximal meansfacing towards the attending physician, i.e. the proximally arrangedcomponents of the device are introduced less far into the blood vesselsystem.

If the phrase ‘longitudinal direction’ is used in this document it is tobe understood as denoting the direction into which the device isadvanced, i.e. the longitudinal axis of the device also coincides withthe longitudinal axis of the blood vessel along which the device ismoved forward.

The inventive device is manufactured in such a way that the fibersultimately forming the brush are placed adjacent to each other and, ifso desired, also superimposed on each other between two core wires, withsaid fibers extending orthogonally to the core wires. It is to be notedin this context that according to the invention an orthogonal extensionshall not exclusively mean an angle of exactly 90° but rather anytransverse configuration of the fibers in relation to the core wires,i.e. the fibers primarily extend transversely to the core wires, not inparallel. Accordingly, also angles of for instance 700 may be viewed asbeing orthogonal in the framework of the invention. After the fibershave been placed between the core wires, said wires are twistedtogether, for example in that one end is fixed while the other one isturned or twisted around the other to bring about a plastic deformationof the core wires thus forming into a spiral structure. After the corewires have been twisted together the fibers project outwardly from thetwisted core wires virtually in the form of a helical line. Asignificant advantage of such a device is that relatively little corewire is required to achieve a very high fiber coverage of the distalelement serving as brush. Having to use only a little amount of corewire also offers benefits in that the system retains high flexibility.Moreover, fixing the fibers at the core wires in this embodiment isparticularly simple and results in the fibers to be distributed over thebrush in very uniform manner.

Quantity as well as density of the fibers can be controlled via thenumber of core wire twistings or windings so that different hardnesscharacteristics can be produced with respect to the radial force exertedby the brush because the higher the number of windings the more fiberscan be arranged per unit of brush length. Moreover, the bendingstiffness of the core can be adjusted, inter alia, via the number ofcore wires and twistings provided. For example, by providing for a greatnumber of twistings or windings of two or more core wires a double helixof these two core wires is formed that is less rigid than with a designwherein fewer windings are provided.

If thought expedient, the at least two core wires may be connected witheach other at the distal end and thus form a loop. In this case only asingle core wire is used that first extends up to the distal end andthen leads back in such a manner that it twists together the twoparallelly arranged lines of the core wire with the fibers arranged inbetween.

At the proximal end the core wires may be connected by means of a coilto additional components of the device located in proximal direction.Such proximally arranged additional components may, in particular,consist of a guide wire or another distal element designed in the formof a brush. A connection with the help of coils of this nature issufficiently known in the field of medical technology, particularly whenocclusion helixes are employed to treat aneurysms. Connecting the coilwith the core wires may be brought about in this case by welding,bonding, soldering or mechanical (i.e. force- and/or form-closed)joining methods.

The core wires may consist of platinum or its alloys, in particular of aplatinum-iridium alloy, stainless steel, nickel-titanium alloys such asnitinol, or of tungsten and tungsten alloys as well as of combinationsof the materials named here.

The core wires and thus the entire brush may have a straightconfiguration or form into a secondary structure, for example be shapedin the form of a wave or helix, i.e. the core wires themselves which aretwisted together are designed such that the core itself has a wave orhelix form. It is to be understood in this context that the differencebetween a wave and a helix is that the geometry of a wave is merelytwo-dimensional whereas a helix has a three-dimensional configuration.Brushes having a wave or helix form offer advantages in terms of animproved cleaning efficiency. In this context the diameter of the helixmay increase either from proximal to distal or from distal to proximal.

In the case of a secondary structure formed by twisted core wires anelongation preventing filament may additionally be run through the innerspace of the secondary structure or external to it, with said filamentruling out an axial extension of the device beyond the nominal length.Elongation preventing filaments of this nature may be made of polymermaterials (e.g. nylon) or metal, such as, for example, nickel-titaniumalloys (nitinol). The filaments in this case are connected both distallyand proximally to the secondary structure formed by the core wires. Theelongation preventing filament itself may have a straight, wave-like orhelix-shaped geometry, with the two latter variants allowing for acertain tolerance or play in longitudinal direction with respect to apossible axial extension. However, to achieve a still sufficientprotection against elongation such a helix should have a very high pitchresulting in the tolerance or play with respect to axial extension to bekept within certain limits.

The core wires mentioned above must not necessarily be conventionalwires having a round cross section but may be provided in the form ofcut or shaped form elements, for example if the core wires are cut froma plate. In this case the cross section of the core wires is not roundbut quadratic or foursquare.

In accordance with another advantageous embodiment the device isprovided with several distal elements from which fibers stick outradially. Such a system consisting of several brushes may, for example,offer benefits if particularly large thrombi or, as the case may be,several thrombi have to be eliminated from the blood vessel system.Furthermore, a brush located farther distally may serve, if need be, tointercept and remove fragments of a thrombus that detach from theproximally arranged brush.

To enable an adequate flexibility to be achieved despite the length ofsuch a system comprising several brush portions it is consideredexpedient to interconnect the individual distal elements by means ofconnecting elements, especially articulated joints. Such an articulatedjoint makes it possible for the device to perform within certain limitsbending movements and thus follow the configuration of the bloodvessels.

As the case may be, several distal elements forming a brush, preferablytwo or three brushes, may be arranged side by side as viewed in thecross section of the device, preferably in parallel. These brushes arein turn interconnected proximally and distally, for example in that thecore wires of the brushes again converge centrally on the proximal anddistal sides. Such an embodiment offers the advantage that eachindividual brush may be provided with shorter fibers because the fibersneed not extend from the center of the device to the inner wall of thevessel but merely from the individual distal elements that are near thevessel walls in the event they are arranged side by side. Since fibersthat are shorter or stick less far out of the distal element are in anycase harder the cleaning efficiency may be improved even more in thisway. If thought expedient, the individual brushes may also be twistedfurther so as to form a helix. Furthermore, the distal elements may beprovided with braces (expediently at least 3) that start out from thedistal end of the distal element, extend radially outward and againconverge centrally at the proximal end of the distal element. The radialextension of the braces preferably corresponds roughly to the radialextension of the fibers. Throughout the middle area the braces thusextend for the main part in parallel with the inner core of the distalelement. The provision of braces on the distal element serves asadditional guide for the system in the blood vessel. To a certain extentthe braces impart a resemblance to cage structures, but the braces inthis case need not be arranged such closely so that it cannot be said inany circumstance that a true cage structure exists.

In cases where the device is provided with several distal elementshaving outwardly projecting fibers the braces may span in each case overone distal element or over several distal elements. In the event of twodistal elements the braces may, for example, extend from the distal endof the distal element located farthest away in distal direction and onlyconverge at the proximal end of the proximal brush. In this case it isexpedient to arrange additional intermediate braces between the bracesand the centrally extending core wires and in this way enhance thestability of the structure formed by the braces.

In accordance with another advantageous embodiment of the invention thebrushes have a tapered structure, i.e. the radial extension of thefibers which eventually corresponds to the brush diameter increases fromproximal to distal. The main advantage of such a tapered brush form isthat irrespective of the width of the blood vessel to be cleaned at atime there are always at least some brush portions the fibers of whichare of optimum length. Fibers have an optimum length for a given bloodvessel especially if the fibers contact the walls of the blood vessel insuch a way that they are not bent in distal direction when the device ismoved proximally. In this case the cleaning efficiency of the fibers isparticularly good. Longer fibers, on the other hand, are bent distallyduring the return movement in proximal direction so that their cleaningefficiency diminishes whereas short fibers may not even reach the innerwall of the vessel and are thus incapable of providing a cleaning effectanyway. Due to the fact that with a tapered brush shape not all fibersare of equal length there are even in the case of varying blood vesselsalways at least some fibers that have an optimum cleaning efficiency.

Preferred is a tapered distal element (brush) wherein the radialextension of the fibers increases from proximal to distal. This can beachieved in that fibers of increasing length are placed from proximal todistal between the core wires. Such a brush offers the advantage thatshould the situation arise the distally arranged longer fibers arecapable of also capturing individual thrombus fragments if the device isretracted in proximal direction. However, tapered brushes are alsoconceivable wherein the radial extension of the fibers increases fromdistal to proximal.

In this case the tapered brushes may be of different shape, and it willbasically be adequate of they are of tapered configuration. However,also several tapered brushes may be provided which are interconnected bymeans of an articulated joint, or many short tapered segments on asingle distal element.

Additionally or alternatively the fibers in the proximal area of adistal element may also be designed to be harder than in the distalarea. The harder fibers in the proximal area in this case mainly serveto scrape off a thrombus adhering to the vessel wall while the softerfibers in the distal area primarily serve to secure or retain thethrombus or fragments of a thrombus. Another possibility warranting thatfibers of different length are provided so that at least some fibersalways have an optimum length is to arrange the individual fibers insuch a way that they have a shorter and a longer side when sticking outon both sides of the core wires twisted around each other. This can bebrought about by placing the fibers, before the core wires are twistedaround each other, not exactly centered between the core wires but in anirregular fashion.

Further possibilities of producing on the distal element fibers ofdifferent length are to use even at the time of twisting differentlylong fibers so that an irregular brush structure is arrived at in thisway or to produce tapered brushes the diameter of which increases fromdistal to proximal. However, more advantageous is the variant describedheretofore wherein the radial extension of the fibers increases fromproximal to distal because the longer fibers in this case are situatedto the rear when the device is retracted in proximal direction so thatthrombus fragments may be intercepted in this way.

To facilitate the capture of a clot (thrombus) the brush of the distalelement may be differently designed along its core. Some areas, forexample, especially the area in the middle of a brush may be providedwith softer fibers, with these fibers serving to retain the clot. Areaslocated further proximally or distally provided with harder fibers onthe other hand are rather intended to produced a more intense cleaningeffect.

A similar effect is achieved if the density of the fiber coverage insome areas is lower, especially in the middle area of the distalelement, than in other areas. This as well produces the effect that theproximal and distal areas of the brush where the fibers are more denselyarranged primarily serve to enhance the cleaning effect on the walls ofthe vessel whereas the less densely covered middle area is intended tocapture the clot.

The fibers placed between the twisted core wires are primarily securedin that they are clamped in place when twisting is carried out. However,further fixation can be achieved additionally or alternatively bybonding, knotting and/or fusing methods.

The fiber ends located radially outward beneficially are provided withslubs or thicker nubs, for example of spherical shape, so that increasedsurface is available for better clot mass retention. Another advantageof this embodiment makes it possible in this way to provide fiber endsthat have an atraumatic effect. The thicker nubs at the ends of thefibers may for example be produced by cutting the fibers with the aid ofmethods like micro-laser cutting, electron beam cutting etc.

In accordance with another embodiment the fiber ends located radiallyoutward are at least partially connected with each other via loops. Thefibers connected in this manner thus comprise or are made up by a singlefiber and not two fibers with the single fiber having a loop-shapedconfiguration. The fiber emerges from the core, extends to the outer rimof the brush where it forms into a loop and then runs back to the core.The fiber in this case extends such that an elliptical shape is formed.This embodiment offers advantages in that, similar to the thicker nubsat the end of the fiber, there is a larger surface available for clotmass retention which results in the thrombus capturing effect beingimproved. Furthermore, the roundness of the loop makes it atraumatic.Also beneficial is that the fibers have increased stiffness due to theloop-shaped fiber configuration exhibiting a behavior similar to that oftwo fibers arranged side by side.

As per a further embodiment the core wires in the cross section of thedistal element extend outside the center, i.e. have eccentric extension.Such a brush with an eccentrically arranged core has the effect that onone side of the brush relatively short fibers are located while longones exist on the other side of the core. As a result of their shortdistance to the core the short ends of the fibers have significantlyharder characteristic and the long fiber ends are significantly softerso that in this case as well the harder fibers rather improve thecleaning effect whereas the softer fibers enable a better retention ofthe captured thrombus. A brush with eccentrically arranged core offersstill another advantage in that such a brush can be maneuvered past theside of a clot more easily and then be retracted so that while the brushmoves back in proximal direction the thrombus is captured.

The brush-shaped devices described hereinbefore may basically be usedfor the filling of aneurysms as well. In such cases the brushes shouldbe designed in the form of a helix which are relatively short incomparison to brushes that serve the purpose of eliminating thrombi. Tobe able to place the brushes into aneurysms the distal element(s) haveto be designed so as to be detachable from the guide wire. To be able tofill the aneurysm more completely the bristles may also be provided withan adhesive or a thrombogeneous coating.

The tapered form of a brush as described earlier where the diameter ofthe distal element increases from proximal to distal has turned out tobe especially advantageous. Aside from a device providing for the abovedescribed arrangement of fixing the fibers between two core wiresanother device is as well basically conceivable for the removal offoreign objects and thrombi from body cavities and blood vessel whereinthe distal element has a tapered form, the diameter of the distalelement thus increasing from proximal to distal or vice versa. Preferredis a tapered form wherein the distal element has a diameter thatdistally is greater than proximally.

In accordance with an alternative embodiment (irrespective of the brushstructure described above) a device with guide wire is provided for theelimination of foreign objects and thrombi from body cavities and bloodvessels, wherein said device is provided with a cage structure at thedistal end of the guide wire which is composed of individual braces andsuited to be flatly collapsible under the external strain exerted by amicro-catheter and capable of being transported inside themicro-catheter and unfolding to its full cage structure as soon as theexternal strain caused by the micro-catheter is omitted, with said cagestructure comprising at least two cages arranged in longitudinaldirection one behind the other.

Such a device with cage structure for the removal of thrombi is inprinciple intended to accommodate thrombi in its interior and in thisway enable thrombi to be eliminated. The cage structure in collapsedcondition is transported inside a micro-catheter through the bloodvessels to the target site where it is then pushed out of themicro-catheter distally of the thrombus to be removed whereupon thedevice unfolds and assumes its full cage structure. The cage structuremay accommodate the thrombi to be removed either completely or infragmented form. Subsequently, the device is retracted through the bloodsystem and, after it has been pulled into a catheter which may beprovided in the form of an additional guide catheter having a greaterinner diameter than the micro-catheter within which the cage structurewas brought to the target site, finally and completely removed from theblood vessel system together with the thrombus.

Generally, the cage structure has an oblong, ship-like structure of alength ranging between 5 and 50 mm with a diameter of between 2 and 6 mmin expanded state. The cage structure is composed of peripheral, inparticular longitudinally extending braces which as a rule are regularlyspaced over the circumference.

According to the invention this cage structure comprises at least twocages arranged in longitudinal direction one after the other so that adouble-cage structure is formed. Two or more successively arranged cagesoffer the advantage that the cages may serve different purposes. Forexample, the proximally arranged cage may serve as cutting tool for thethrombus or clot that has formed within the vessel whereas the distalcage serves to accommodate the thrombus or the fragments of it. Such afragmentation of the clot is of special significance if the clot in itsentirety is too big to be accommodated entirely within the cagestructure or has hardened to such an extent that it is very difficult tomaneuver it into the cage structure. It is to be assumed that especiallyolder thrombi show such hardening tendencies.

As mentioned earlier, the cage structure is composed of braces whichpreferably extend at least partially in longitudinal direction. It is tobe noted in this respect that by ‘braces extending in longitudinaldirection’ not only braces are meant that are running exactly parallellyto the longitudinal axis but also those extending at a certain degree of<90° to the longitudinal axis in distal or proximal direction. It is tobe noted further that in order to form a true cage structure it mustpreferably be composed of at least three, but even better of four toeight braces. It is also considered expedient for the cage structure andthus the braces to be made of shape-memory material, preferably nitinol,which enables said structure to be transported in folded-up condition ina micro-catheter and unfold automatically when released from themicro-catheter.

The process of unfolding to the full cage structure upon omission of theexternal strain exerted by the micro-catheter must not necessarily takeplace automatically but may also be effected manually. For example, anadditional guide wire may be attached to the cage structure which causesthe cage structure to unfold when being advanced.

Expediently, a core filament extends centrally through the cagestructure. This core filament constitutes the distal segment of theguide wire or is a separate core filament serving as continuation of theguide wire in distal direction.

Folding up of the cage structure under the influence of the externalconstraint caused by a catheter is normally associated with a stretchingof the cage structure. To counteract this stretching or facilitateradial expansion associated with a longitudinal contraction when thecage structure is released from the catheter it will be expedient forthe cage structure to be movably designed allowing it to follow thesestretching/contraction movements. Therefore, the cage structure shouldbe movable relative to the core filament at least at its proximal end.This can be achieved in such a manner that the cage structure terminatesin a sleeve at its proximal end through which the core filament movablyextends in longitudinal direction.

Since with the inventive double-cage structure the cage arranged furtherdistally shall primarily serve as cutting tool for the clot to beremoved whereas the distal cage is intended to accommodate the clot, itis considered expedient to appropriately design the cages such that theycan fulfill their duty optimally. To this end the distally located cagemay thus be designed to be longer for instance to make availablesufficient space for the thrombus to be taken in. On the other hand, theproximal cage intended to fragment the thrombus may be designed to beshorter in longitudinal direction.

Considering the necessity that the proximally arranged cage must exertsuch forces on the thrombus that are necessary to fragment it, it ismoreover deemed expedient to design this cage so as to be harder thanthe distally arranged cage. A harder design in this context is to beunderstood such that the radial forces required to bring aboutdeformation are higher than the radial forces necessary to deform thedistally arranged cage. By providing an appropriately hard design forthe proximally arranged cage even very old and already severely hardenedthrombi can be scraped off the vessel wall or fragmented to such anextent that after they have been accommodated in the distally arrangedcage they may be eliminated from the blood vessel.

To enable the proximally and distally arranged cages to fulfill theirduty they can be manufactured of different materials, and for thispurpose a harder material should be used for the proximal cage asmentioned above. For example, different nitinol materials may be usedhere, i.e. especially different alloys. Alternatively or additionallyalso the braces of which the proximally arranged cage is formed may havea greater diameter than the braces of which the distally arranged cageis composed. In this way it is ensured as well that the proximal cagenot only is harder but also capable of withstanding higher radialforces.

It is also possible in this context to select a suitable angledetermining the position of the braces in relation to the longitudinalaxis. The braces of which the proximally arranged cage is made may thusextend in relation to the longitudinal axis at least partially at anangle greater than that of the braces of the distally arranged cagewhich results in the proximally arranged cage to be less easilycollapsible by radial forces. The distally arranged cage thus has asomewhat flatter structure which will be noticeable particularly if thedistal cage is designed to be longer than the proximal cage.

In cases where on account of extraordinarily big thrombi the amount ofclot material to be taken in is particularly great cage structures maybe employed that comprise more than two cages. All the cages thusprovided distally of the proximally arranged cage will then serve toaccommodate clot material.

As mentioned above, the cages may be composed of braces of differentnumber with the highest cage density being achieved of course in thecage that has been provided with the greatest number of braces. It hasturned out, however, that depending on application it may be expedientnot to provide too many braces lest the proximal opening of the cagestructure through which the thrombus shall enter the cage structure maybe too small. Viewed in the proximal cross section of the cage structurethe partial openings between the braces will be all the greater thefewer braces are provided. This is of special significance if thethrombus is rather old and thus firm and coherent and creates problemswhen it is attempted to capture it through the openings in the cagestructure. To handle thrombi of this type it has turned out to beespecially advantageous to provide for a number of braces rangingbetween four and six.

Conceivable are of course also combinations configured in such a waythat the proximal cage which the thrombus must first enter when the cagestructure is retracted within the blood vessel system is provided withfewer braces than the distally arranged cage which is designed toaccommodate the thrombus already fragmented by the proximal cage.

The braces of each cage usually meet at the distal and at the proximalend of the cage each in a point which is preferably arranged centrally.At the points where the braces converge the braces may be connected witheach other directly or indirectly by means of a connecting element. Ifthought expedient the connecting element may be designed in the form ofa sleeve which in relation to a centrally extending core filament islongitudinally movable so as to facilitate in this way stretching andcontraction of the cage structure when moved into or out of thecatheter.

Besides the above described approach of reducing the number of bracesthere is another method by means of which the proximal opening of thecage structure can be made larger, said method providing for the partialopenings existing between the braces to be enlarged at least partially,so that in this manner a strongly coherent thrombus is allowed to entermore easily. For this purpose the large partial openings existingbetween the braces are enlarged which in turn causes the size of smallpartial openings to reduce. This can be brought about by arranging thebraces of at least one cage, preferably the proximally arranged cage,such that they extend, with the cage structure unfolded, from the pointwhere the braces at the proximal cage end converge, in groups along afirst section, e.g. in pairs close to each other in distal direction,then diverge distally to this first section, and in a second sectiondistally to the first section extend equally distributed in distaldirection over the circumference of the cage. In other words, the bracesdo not uniformly extend along the entire cage equally spaced over thecircumference but such an equal distribution is provided in distaldirection only some distance away from the proximal opening. Due to thefact that the braces at the proximal end of the cage initially aregrouped close to each other, partial openings are created the size ofwhich giving the impression as if only half or a third of the number ofbraces were used. In case a total of four braces are provided two pairsof braces each run together for example at the proximal opening so thattwo significantly enlarged partial openings are created which are almostsemicircular whereas the remaining small partial openings left betweenthe braces closely adjacent to each other can be neglected. Similarly,if a total of six braces are provided with said braces initiallyextending in pairs, partial openings almost the size of a third of acircle would be produced. If along the first section three braces eachare arranged close to each other in distal direction, two almostsemicircular openings are even created if six braces are provided.Basically, such an approach providing for the partial openings to beenlarged in part is of course also conceivable in the event of cagestructures that merely consist of a single cage.

The braces forming the cages may be of identical design for the proximaland distal cage. In this case the braces will extend from the proximalend of the proximally arranged cage to the distal end of the distallylocated cage. To make sure that the braces form a double-cage structureand do not merely build up a greatly extended cage they will preferablycross each other at least partially so that the junction point where thebraces meet constitutes the distal end of the proximally arranged cageand at the same time the proximal end of the distally located cage. Suchan embodiment offers the advantage that the radial forces being exertedon the distal cage and on the proximal cage will influence each otherbecause the radial forces in the braces are transmitted to the othercage. In this manner the device may retain its unfolded shape even ifthe nominal diameter cannot be realized in a given vessel. This isparticularly true if the measures for a length adjustment of the cagestructure as described hereinbefore have been provided.

At the junction point the braces may be interconnected and/or attachedto the core filament. Preferably, no connection will be provided,however, because the radial forces effect will not be disturbed in thismanner.

Furthermore, the radial forces may also be influenced by not entirelypushing the device out of the micro-catheter. For example, if only thedistal cage is moved out whereas the proximal one is kept within themicro-catheter the radial force of the distally arranged cage increases.This may be advantageous in the event especially firm clots/thrombi haveto be retrieved.

The radial forces will influence each other particularly well if fromthe proximally arranged cage to the next distally located cage thebraces are run to the opposite side of the cage structure, i.e. if thereis an offset by 180° from one cage to the next.

The cage arranged farthest in distal direction may expediently bedesigned to have a net structure at least distally so as to provideincreased safety against losing thrombus fragments that may slip out ofthe cage when the device is retracted out of the blood vessel. This netstructure may in particular be composed of braided wire for which, sameas for the braces, nitinol can be used. Expediently, such a netstructure of a cage is arranged especially at the distal end because forthe removal of the thrombus the cage structure after all is moved inproximal direction so that a net structure located at the proximal endof the cage would be less desirable as it could in fact prevent thethrombus from entering the cage. Accordingly, the net structure shouldonly be located at the distal end of the cage or should become morefine-meshed from proximal to distal. Moreover, a greater mesh size inthe proximal area of the cage facilitates the retraction of the cageinto the catheter with the structures collapsing and containing thethrombus.

A function similar to that of the net structure just described can alsobe achieved by providing a cover on the distal side of the distallyarranged cage in the form of a polymer skin. Providing such a polymerskin which may for example consist of expanded PTFE(polytetrafluoroethylene) results in the distal end of the cage forminga bag-like structure. The polymer skin in this case extends from thedistal tip of the cage along the braces on to a desired position, forexample to roughly the middle of the cage. At the distal end of the cagethe polymer skin may be provided with one or several openings of a sizebig enough to allow liquid, especially blood, to pass through withoutdifficulty whereas the thrombus or fragments of a thrombus captured bymeans of the cage structure are retained. This is advantageous, inparticular, when the cage structure is retracted because such aconfiguration will in fact not impair the flow of blood while thethrombus itself can be completely eliminated from the blood vesselsystem.

As per another beneficial embodiment the braces of the cage structureare arranged in a helical fashion, i.e. the distal end and the proximalend are offset against each other by an angle ranging between 45° and180°, preferably by approx. 90°. Such a helical line arrangement allowsa thrombus adhering to a vessel wall to be sheared or cut off when thecage structure is moved forward without the necessity of having to turnto device.

In accordance with another variant the braces extend along a wave linewith a lateral deflection of between 45° and 90°, i.e. the braces atfirst extend in lateral direction until they have reached for instance apoint offset by 90° to the starting point and then along the second halfof their length extend back to the starting point. In this case theproximal end and the distal end are not offset against each other.

In accordance with an especially preferred embodiment the device notonly comprises a cage structure arranged at the distal end of the guidewire but in the area of the cage structure has additionally beenprovided with fibers or bristles projecting radially outward, with saidfibers or bristles being arranged individually or in bundles.

The fibers or bristles are connected with a distal element of the guidewire in a manner known per se, for example, as is known from thefabrication of fiber-equipped embolization spirals. This may be achievedthrough entwinement with the distal element, by gluing, welding or anyother suitable fastening method.

Advantageously, the device is provided with one or several radiopaquemarkers. These may, for example, be made of platinum or a platinumalloy. Radiopaque markers of this kind may be located both in areas fromwhich the fibers or bristles emanate and as well on the cage structureto enable the attending physician to monitor the treatment with the helpof image-forming methods conducive to the purpose.

Moreover, it is considered advantageous if the tip of the entire deviceis designed so as to be atraumatic, i.e. is rounded off for example.

The distal element of the device which is provided with fibersexpediently extends centrally in the cage structure, i.e. thefiber-covered element is in fact located in the center of the cages. Inthis manner, the beneficial effect of the cage structure on the one handand those of the fibers arranged on the distal element on the other arecombined with each other. This design enables the captured thrombus tobe secured and retained most safely both by means of the cage structureand the fibers so that the thrombus can be retrieved and drawn into acatheter.

The fibers or bristles may be arranged on and attached to inparticularly one or several movable filaments located on the corefilament extending through the cage structure so that thefibers/bristles virtually stick out radially from the cage structure inradiated form. The movable filament may, for example, consist of ahelically wound wire. Alternatively or additionally, fibers or bristlesmay also be secured to the braces of the cage structure.

It shall, furthermore, be observed also with respect to the embodimentof the invention relating to a cage structure that with respect to thefibers all comments made hereinbefore in the context of the brush-likedistal element shall apply as well, in particular regarding the materialused for the fibers, the angular alignment, the length of the fibers,the coating of the fibers, the use of radiopaque markers etc.

Moreover, all the described embodiments of the invention may be combinedwith each other. Especially, the embodiment providing for a double-cagestructure may have additional fibers, whereas, on the other hand theembodiment providing for fibers emanating from the distal element mayadditionally have a cage structure. In particular, a combination ofdouble-structure and distal element composed of core wires twistedaround each other with outwardly protruding fibers is also possible.

Eventually, the invention also relates to the combination of the devicewith a guide and/or micro-catheter in which the device is maneuvered tothe application site and when filled with the thrombus removed from theblood vessel system. It may be expedient to additionally design thecatheter in the form of an aspiration catheter capable of accommodatingmicro-catheters.

The above described invention is of special significance to the removalof thrombi from vessels of especially small lumen, in particularintracranial. The invention may of course be used also for theelimination of thrombi from other parts of the body, for example theheart, lungs, legs etc. However, the invention may also be used for theremoval of other foreign objects from blood vessels, for exampleremoving embolization spirals and stents.

Further elucidation of the invention is provided by way of examplesthrough the enclosed figures, where

FIG. 1 shows the making of a brush-like distal element;

FIG. 2 a is a longitudinal section of the distal element;

FIG. 2 b is a longitudinal section of the distal element;

FIG. 2 c is a cross-sectional view of the distal element;

FIG. 3 shows an embodiment with tapered brush;

FIG. 4 is a longitudinal view of another embodiment of the distalelement;

FIG. 5 shows a distal element provided with a wave-like core;

FIG. 6 shows a helically extending core;

FIG. 7 illustrates a helically extending core with outwardly protrudingfibers;

FIG. 8 shows an embodiment with two distal elements arranged insuccession;

FIG. 9 shows an embodiment with two distal elements arranged one afterthe other and additional braces;

FIG. 10 shows another embodiment with two distal elements arranged oneafter the other and with additional braces;

FIG. 11 shows an embodiment with tapered brush elements;

FIG. 12 shows a further embodiment with tapered brush elements;

FIG. 13 shows an embodiment with fibers having different hardnesscharacteristics;

FIG. 14 shows an embodiment with a fiber coverage of different density;

FIG. 15 a is a longitudinal view of an embodiment with eccentricallyarranged core;

FIG. 15 a is a cross-sectional view of an embodiment with eccentricallyarranged core;

FIG. 16 shows an embodiment with cage structure and brush element;

FIG. 17 a is a side view showing a double-cage structure;

FIG. 17 b shows the double-cage structure of FIG. 17 a viewed fromdistal end;

FIG. 18 a shows another side view of a double-cage structure;

FIG. 17 b illustrates the double-cage structure of FIG. 18 a viewed fromdistal end;

FIG. 19 a is the proximal view of a cage structure in accordance with anembodiment;

FIG. 19 b is the proximal view of a cage structure in accordance with analternative embodiment;

FIG. 20 a is the proximal view of a cage structure in accordance withanother embodiment;

FIG. 20 b is the proximal view of a cage structure in accordance withanother embodiment;

FIG. 20 c is the proximal view of a cage structure in accordance withanother embodiment;

FIG. 21 is a side view of the cage structure shown in FIG. 20 a;

FIG. 22 shows a side view of another embodiment of the invention.

The invention is elucidated by way of FIG. 1 which shows two core wires14 arranged in parallel, with orthogonal fibers 6 being arranged betweenthe two core wires 14. Subsequently, the core wires 14 are restrained atlocation 15 and twisted around each other by performing a torsionalmovement T. In this way a brush-like distal element 27 is obtained fromwhich fibers 6 are projecting radially outward.

When core wires 14 have been twisted around each other the distalelement 27 appears as shown in FIGS. 2 a to 2 c, said FIGS. 2 a and 2 bbeing longitudinal sections, whereas FIG. 2 c shows a view from theproximal or distal end. It can be seen that the fibers 6 are equallydistributed over the circumference of the distal element 27 and protuderadially outward.

In FIG. 3 an embodiment is shown wherein the brush-like distal element27 is has a tapered shape, i.e. its diameter increases from proximal todistal. The proximal diameter A typically ranges between 1 and 3 mm, thedistal diameter B between 2 and 5 mm. The length of the distal element27 is in the range of between 10 and 20 mm, the length D of guide wire18 for example is 3000 mm. As a rule, core 14 will consist of core wirestwisted around each other, however tapered brush forms provided withfibers 6 attached to core 14 by some other method are conceivable aswell. Moreover, the device is fitted with radiopaque markers 9 arrangedat the proximal and distal end of the distal element 27.

FIG. 4 illustrates another embodiment of the inventive distal element 27wherein fibers 6 are shown as a consistent, homogeneous area produced onaccount of the density of the fiber coverage. In this case the corewires 14 at the distal end of the distal element are connected with eachother via a loop 16 so that in fact a single core wire 14 exists thatextends from proximal to distal where it forms into a loop and thenextends back in proximal direction. In this way both ends of core wire14 are thus twisted around each other.

It is also evident from FIG. 4 how the distal element 27 can be attachedvia a helix 17 to other components of the device located fartherproximally, in particular to a guide wire 28.

In FIG. 5 an extension of core wire 14 is shown in a wave-like orsine-wave form. Fibers 6 as well follow this wave-like extension whichis thus provided for the entire distal element 27. In comparison to corewires 14 of straight configuration this results in an improved cleaningefficiency.

From FIG. 6 a helical secondary structure of core 14 can be seen, withthe fiber structure not being shown here for the sake of simplifying therepresentation. It is to be noted in this case as well that core 14 isalso composed of at least two core wires 14 twisted around each otherand forming a primary helix comprising of twisted core wires 14. Thesecondary helix shown in FIG. 6 must therefore not be confused with aprimary helix arrived at by twisting core wires 14 together. A helicalstructure of the distal element offers advantages in that the innerwalls of vessels are cleaned more efficiently and, moreover, such anembodiment may serve to place shorter brushes into an aneurysm for thepurpose of occluding the same.

Another representation of a helical distal element can be seen from FIG.7 which is a longitudinal section showing the fiber coverage 6 as aschematic view.

FIG. 8 shows an embodiment of the invention consisting of several distalelements 27. Each distal element 27 is composed of core wires 14 twistedaround each other and provided with a fiber coverage 6. Distal elements27 in this case are connected with each other by articulated joint 20 sothat a certain degree of flexibility is achieved when advancing andretracting the device within vessels. At the proximal end the distalelement is attached via a coil 17 to a push or guide wire 18. At thedistal end the device is provided with a rounded tip 19. Since fibers 6of the two distal elements 27 have different characteristics in thisexample, a different color shading has been selected here.

Another embodiment is shown in FIG. 9 which shows several distalelements with said embodiment largely corresponding to the one depictedin FIG. 8. However, the device additionally has braces 21 extending fromthe distal end of the distal element 27, projecting radially outward andagain joining centrally at the proximal end of the distal element 27.The radial extension of the braces 21 in this case coincides with theradial extension of the fibers 6. Such an embodiment comprisingadditional braces 21 serves to improve the guidance of the system withinthe vessel.

Another embodiment with braces can be seen from FIG. 10 wherein thebraces 21 extend along and over all distal elements 27. Additionalstabilization in this case is obtained, however, by providingintermediate braces 22.

In FIG. 11 an embodiment with two distal elements is shown with eachdistal element 27 having a tapered structure. The radial extension ofthe fibers of distal elements 27 increases here from proximal to distal,i.e. in each case the distal elements 27 are wider in the distal than inthe proximal area. Such an embodiment has the benefit in thatirrespective of the blood vessel width fibers 6 are always availablethat are of optimum length.

In FIG. 12 another embodiment is shown wherein within each distalelement 27 the radial extension of the fibers increases from proximal todistal several times. Accordingly, each distal element 27 consists ofseveral tapered brushes.

FIG. 13 illustrates an embodiment wherein the center area 24 of thedistal element 27 has been provided with softer fibers, whereas in theproximal as well as distal area 23 harder fibers have been arranged. Inthis case the center area 24 primarily serves to accommodate clots whilethe proximal and distal areas 23 are designed to intensify the cleaningeffect.

Likewise, the embodiment shown in FIG. 14 serves a similar purpose withthe exception that a similar effect is brought about here due to thefiber coverage in area 26 being thinner than in proximal and distalareas 25.

From FIGS. 15 a and 15 b a distal element 27 can be seen as alongitudinal section as well as a proximal/distal view wherein thetwisted core wires 14 extend eccentrically. Accordingly, fibers 6project significantly farther on one side than on the other. This isespecially advantageous if the distal element 27 must be moved laterallypast a thrombus.

FIG. 16 shows an embodiment wherein a cage structure 3 has been combinedwith a brush structure. The distal element 27 here also consists of corewires 14 twisted around each other and fibers 6 radially projectingoutward, with said element being arranged proximal to cage 3. The cage 3has a polymer skin 10 with transverse braces 11 connecting the polymerskin 10 with braces 4. Furthermore, the device comprises radiopaquemarkers 9 and a guide wire 18. Upon retraction of the device in proximaldirection a thrombus is initially captured and secured by means of thedistal element 27 via fibers 6. In the event individual thrombusfragments become split off these are retrieved by action of the distallyarranged cage structure 3 with its polymer skin 10 because polymer skin10 is purposefully designed to form a pocket. As a result of brushstructure and cage structure being combined an especially advantageousdevice for the removal of thrombi is provided.

As per an alternative embodiment of the invention FIG. 17 a represents acage structure 1 consisting of a proximal cage 2 and a distal cage 3 inaccordance with the invention. The two individual cages 2, 3 in thiscase are formed in that the braces 4 that form the cages 2, 3 cross eachother at the center, with said braces of the proximal cage 2 beingoffset in relation to the distal cage 3 by 180° each. A core filament 5extends centrally through the cage structure 1 and is connected tobraces 4 at the distal end whereas the braces 4 at the proximal end aremovably designed in relation to the core filament 5. In this way thecage structure 1 is capable of being moved to a certain extent inlongitudinal direction which is important when the cage structure 1 ismoved into or discharged out of a micro-catheter.

Since both cages 2, 3 are formed by the same braces 4 it is ensured thatradial forces are transmitted from one cage to the next, and, forexample, radial forces acting on the proximal cage 2 increase theoutwardly acting radial forces exerted by the distal cage 3. Forexample, for the retrieval of particularly firm thrombi only the distalcage 3 may be pushed out of a micro-catheter while the proximal cage 2is left inside the micro-catheter so that as a result of the externalconstraint the micro-catheter exerts on the proximal cage 2 theoutwardly acting radial force of distal cage 3 is significantlyincreased.

It must be pointed out in this context that FIG. 17 a is merely aschematic representation which only show two braces 4. For the formationof the cage structure 1 more braces 4 are usually used, for examplethree to six braces 4.

FIG. 17 b shows the cage structure 1 of FIG. 17 a viewed from the distalend. The core filament 5 extends through the center whereas, viewed inlongitudinal direction, the braces 4 turn around the core filament 5forming a right-hand helix.

FIG. 18 a is a side view of another cage structure 1 wherein theproximal cage 2 is arranged on the left-hand side and the distal cage 3on the right-hand side. Four braces 4 each are shown here that form bothcages 2, 3 and intersect at a junction point 8 located between the twocages 2, 3. Through the cage structure 1 a core filament 5 extends onwhich filaments 7 are arranged movable in longitudinal direction, saidfilaments being reinforced through fibers 6 projecting radially outward.These fibers 6 are flexible such that when the device is moved forwardthrough a micro-catheter they fold in the direction of the longitudinalaxis but when the device has been discharged from the micro-catheterassume an upright position. Fibers 6 serve the purpose of additionallysecuring a captured thrombus and, moreover, have a stabilizing effectwhich results from the thrombogeneous coating of the fibers 6. Both atthe distal end and at the proximal end of the cage structure 1radiopaque markers 9 are arranged by means of which the system can bemonitored with the aid of image-forming methods. Core filament 5 isinterrupted at the point marked by a circle so that upon contraction orunfolding of the cage structure 1 the proximal portion of the corefilament 5 is allowed to move to and from in longitudinal directionwithin the filament 7. In this manner the longitudinal expansion andcontraction of the cage structure 1 is significantly facilitated. Theradiopaque marker 9 located at the distal end of the device has arounded tip which has an atraumatic effect.

FIG. 18 b is a view of the cage structure 1 illustrated in FIG. 18 a asseen from the distal end showing six braces 4 equally distributed overthe circumference. Fibers 6 in this case are arranged in bundlesprojecting radially outward. Core filament 5 again forms thelongitudinal axis.

In FIGS. 19 a and 19 b views of proximal openings of a cage structurecan be seen, with the cage structure shown in FIG. 19 a being composedof four, the cage structure in FIG. 19 b of six braces 4. On the onehand, using six braces 4 brings about a more enclosed cage structure 1,but if only four braces 4 are arranged the proximal openings of the cagestructure 1 between braces 4 will be significantly larger. The latterarrangement may be advantageous in the event of especially firm andcoherent thrombi because in this manner the thrombus can be more easilymaneuvered through the proximal opening into the cage structure 1.

In FIGS. 20 a, 20 b and 20 c an alternative arrangement is illustratedby means of which the partial openings 12, 13 existing between thebraces 4 can be made larger. In this case, the braces 4 at the proximalend of the cage structure 1 emanate from a common point and initiallyextend in distal direction in groups close to each other and in parallelbefore they diverge at a point somewhat farther distally of a firstsection and finally assume their end position in which the braces 4 areequally distributed over the circumference of the cage. If four bracesare used four partial openings are obtained as already shown in FIG. 19a but due to the novel configuration of the braces the large partialopenings 12 are significantly enlarged whereas the size of the smallpartial openings 13 is considerably reduced. On account of braces 4extending close to each other in pairs and parallel partial openings 12,13 are created which almost coincide with the partial openings thatwould exist if only half the number of braces 4 were used, i.e. in FIG.20 a the proximal opening is cut into halves nearly, in FIG. 20 b wheresix braces 4 are shown approximately into thirds. In FIG. 20 c threebraces 4 each initially extend in groups close to each other so that twoapproximately semicircular partial openings 12 are created although atotal of six braces 4 are arranged.

FIG. 21 again illustrates as a side view the cage structure 1 shown inFIG. 20 a where it can be seen that starting out from marker 9 thebraces 4 initially extend parallelly in pairs before they diverge andare equally distributed over the circumference of the cage structure 1.It is to be observed in this case that FIG. 21 only shows one cage ofthe cage structure 1 with the center portion having been omitted.

From FIG. 22 another cage structure 1 can be seen with only the distalcage 3 being shown here. Said cage consists of four braces 4 extendingbetween two radiopaque markers 9. Core filament 5 runs centrally throughthe cage structure 1. The special feature of the embodiment shown inFIG. 22 is the polymer skin 10 arranged at the distal end of the cagestructure 1. Arranged transversely to braces 4 cross braces 11 can beseen which in each case constitute the limit of the polymer skin 10 inproximal direction. This design provides for a pocket being formed atthe distal end of the cage structure 1 which serves to accommodate athrombus. The transversely extending connecting braces 11 serve tostabilize the edge structure of the polymer skin 10 and additionallysecure the braces in relation to each other.

1. Device for the removal of foreign objects and thrombi from bodycavities and blood vessels comprising a guide wire (18) provided withone or several distal elements (27), characterized in that the distalelement (27) consists of at least two core wires (14) which are twistedaround each other and between which fibers (6) are arranged transverselyto the extension of the core wires (14), with said fibers (6) beingtwisted together with the core wires (14) so that the fibers (6) projectradially outward from the distal element (27).
 2. Device according toclaim 1, characterized in that the core wires (14) are connected witheach other at the distal end in such a way that they form a loop (16).3. Device according to claims 1 or 2, characterized in that the corewires (14) are connected at their proximal end via a coil (17) withother, proximally arranged components of the device.
 4. Device accordingany one of claims 1 to 3, characterized in that the core wires (14) aremade of platinum or a platinum alloy, platinum-iridium, anickel-titanium alloy, tungsten, a tungsten alloy, stainless steel or acombination thereof.
 5. Device according to any one of the claims 1 to4, characterized in that the twisted core wires (14) extend in astraight line.
 6. Device according to any one of the claims 1 to 4,characterized in that the twisted core wires (14) form a secondarystructure.
 7. Device according to claim 6, characterized in that anelongation preventing filament extends through the inner space of thesecondary structure or external to the secondary structure.
 8. Deviceaccording to claim 7, characterized in that the elongation preventingfilament is designed in the form of a straight, wave-like or helicalwire.
 9. Device according to claim 7, characterized in that theelongation preventing filament consists of a polymer material. 10.Device according to any one of the claims 6 to 9, characterized in thatthe twisted core wires (14) have a wave-like configuration.
 11. Deviceaccording to any one of the claims 6 to 9, characterized in that thetwisted core wires (14) are designed in the form of a helix.
 12. Deviceaccording to claim 11, characterized in that the diameter of the helixincreases from distal to proximal or from proximal to distal.
 13. Deviceaccording to any one of the claims 1 to 12, characterized by severaldistal elements (27) from which fibers (6) protrude radially outward.14. Device according to claim 13, characterized in that the distalelements (27) are connected with each other by articulated joints (20).15. Device according to claim 13, characterized in that the distalelements (27) are arranged side by side viewed in a cross-sectionalrepresentation.
 16. Device according to claim 15, characterized in thatthe distal elements (27) are twisted around each other to form a helix.17. Device according to any one of the claims 1 to 16, characterized inthat the distal elements (27) are provided with braces (21) starting outfrom the distal end of the distal element (27), extend radially outwardand again converge centrally at the proximal end of the distal element(27).
 18. Device according to claim 17, characterized in that the braces(21) span over several distal elements (27).
 19. Device according toclaim 17 or 18, characterized in that additional intermediate braces(22) are arranged between braces (21) and the centrally extending corewires (14) of the distal element (27).
 20. Device according to any oneof the claims 1 to 19, characterized in that the radial extension of thefibers (6) of the distal element (27) increases from proximal to distal.21. Device according to any one of the claims 1 to 20, characterized inthat the fibers (6) in the proximal area of the distal element (27) areharder than in the distal area of the distal element (27).
 22. Deviceaccording to any one of the claims 1 to 20, characterized in that thefibers (6) in the middle area of the distal element (27) are softer thanin the proximal and distal area of the distal element (27).
 23. Deviceaccording to any one of the claims 1 to 22, characterized in that thedensity of the fiber coverage in the middle area of the distal element(27) is lower than in the proximal and distal area of the distal element(27).
 24. Device according to any one of the claims 1 to 23,characterized in that the fibers (6) are secured or attached to the corewires (14) by clamping, bonding, knotting and/or fusing.
 25. Deviceaccording to any one of the claims 1 to 24, characterized in that theends of the fibers (6) located radially outward are provided with slubsor nubs.
 26. Device according to any one of the claims 1 to 25,characterized in that the ends of the fibers (6) located radiallyoutward are at least in part connected with each other by means ofloops.
 27. Device according to any one of the claims 1 to 26,characterized in that the fibers (6), at least partially, protrudedifferently far radially outward at both sides of the distal element(27).
 28. Device according to any one of the claims 1 to 27,characterized in that the core wires (14) in the cross sectional area ofthe distal element (27) are arranged and extend eccentrically. 29.Device according to any one of the claims 1 to 28, characterized in thatthe brush structure formed by one or several distal elements is suitableto be flatly collapsible under the external strain exerted by amicro-catheter and transported inside the micro-catheter and unfolds toits full brush structure when said external strain caused by themicro-catheter is omitted.
 30. Device according to any one of the claims1 to 29, characterized in that the distal elements (27) are designed soas to be detachable from the guide wire (18).
 31. Device according toany one of the claims 1 to 30, characterized in that the deviceadditionally is provided with an elongated cage structure which issuitable to be flatly collapsible under the external strain exerted by amicro-catheter and transported inside the micro-catheter and unfolds toits full cage structure when said external strain caused by themicro-catheter is omitted.
 32. Device according to any one of the claims1 to 31, characterized in that the fibers (6) form an angle withlongitudinal axis of the device that ranges between 70° and 110°,preferably between 80° and 90°.
 33. Device according to any one of theclaims 1 to 32, characterized in that the fibers (6) have been providedwith a coating.
 34. Device according to any one of the claims 1 to 31,characterized by one or several radiopaque markers (9).
 35. Deviceaccording to any one of the claims 1 to 34 in combination with a guidecatheter and/or micro-catheter.
 36. Device according to claim 35,characterized in that the guide or micro-catheter is designed asaspiration catheter.
 37. Method for the manufacture of a distal element(27) forming part of a device according to claim 1, characterized inthat at least two core wires (14) are arranged parallel to each other,between which fibers (6) are arranged transversely to the extension ofthe core wires (14), with said core wires (14) being twisted around eachother.
 38. Device for the removal of foreign objects and thrombi frombody cavities and blood vessels comprising a guide wire (18) providedwith one or several distal elements (27), with the distal element (27)being provided with fibers (6) projecting radially outward,characterized in that the distal element (27) has a tapered shape. 39.Device according to claim 38, characterized in that the diameter of thedistal element (27) increases from proximal to distal.
 40. Deviceaccording to claim 38, characterized in that the diameter of the distalelement (27) increases from distal to proximal.